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1/*
2 * driver.c - driver support
3 *
4 * (C) 2006-2007 Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
5 * Shaohua Li <shaohua.li@intel.com>
6 * Adam Belay <abelay@novell.com>
7 *
8 * This code is licenced under the GPL.
9 */
10
11#include <linux/mutex.h>
12#include <linux/module.h>
13#include <linux/sched.h>
14#include <linux/sched/idle.h>
15#include <linux/cpuidle.h>
16#include <linux/cpumask.h>
17#include <linux/tick.h>
18#include <linux/cpu.h>
19
20#include "cpuidle.h"
21
22DEFINE_SPINLOCK(cpuidle_driver_lock);
23
24#ifdef CONFIG_CPU_IDLE_MULTIPLE_DRIVERS
25
26static DEFINE_PER_CPU(struct cpuidle_driver *, cpuidle_drivers);
27
28/**
29 * __cpuidle_get_cpu_driver - return the cpuidle driver tied to a CPU.
30 * @cpu: the CPU handled by the driver
31 *
32 * Returns a pointer to struct cpuidle_driver or NULL if no driver has been
33 * registered for @cpu.
34 */
35static struct cpuidle_driver *__cpuidle_get_cpu_driver(int cpu)
36{
37 return per_cpu(cpuidle_drivers, cpu);
38}
39
40/**
41 * __cpuidle_unset_driver - unset per CPU driver variables.
42 * @drv: a valid pointer to a struct cpuidle_driver
43 *
44 * For each CPU in the driver's CPU mask, unset the registered driver per CPU
45 * variable. If @drv is different from the registered driver, the corresponding
46 * variable is not cleared.
47 */
48static inline void __cpuidle_unset_driver(struct cpuidle_driver *drv)
49{
50 int cpu;
51
52 for_each_cpu(cpu, drv->cpumask) {
53
54 if (drv != __cpuidle_get_cpu_driver(cpu))
55 continue;
56
57 per_cpu(cpuidle_drivers, cpu) = NULL;
58 }
59}
60
61/**
62 * __cpuidle_set_driver - set per CPU driver variables for the given driver.
63 * @drv: a valid pointer to a struct cpuidle_driver
64 *
65 * Returns 0 on success, -EBUSY if any CPU in the cpumask have a driver
66 * different from drv already.
67 */
68static inline int __cpuidle_set_driver(struct cpuidle_driver *drv)
69{
70 int cpu;
71
72 for_each_cpu(cpu, drv->cpumask) {
73 struct cpuidle_driver *old_drv;
74
75 old_drv = __cpuidle_get_cpu_driver(cpu);
76 if (old_drv && old_drv != drv)
77 return -EBUSY;
78 }
79
80 for_each_cpu(cpu, drv->cpumask)
81 per_cpu(cpuidle_drivers, cpu) = drv;
82
83 return 0;
84}
85
86#else
87
88static struct cpuidle_driver *cpuidle_curr_driver;
89
90/**
91 * __cpuidle_get_cpu_driver - return the global cpuidle driver pointer.
92 * @cpu: ignored without the multiple driver support
93 *
94 * Return a pointer to a struct cpuidle_driver object or NULL if no driver was
95 * previously registered.
96 */
97static inline struct cpuidle_driver *__cpuidle_get_cpu_driver(int cpu)
98{
99 return cpuidle_curr_driver;
100}
101
102/**
103 * __cpuidle_set_driver - assign the global cpuidle driver variable.
104 * @drv: pointer to a struct cpuidle_driver object
105 *
106 * Returns 0 on success, -EBUSY if the driver is already registered.
107 */
108static inline int __cpuidle_set_driver(struct cpuidle_driver *drv)
109{
110 if (cpuidle_curr_driver)
111 return -EBUSY;
112
113 cpuidle_curr_driver = drv;
114
115 return 0;
116}
117
118/**
119 * __cpuidle_unset_driver - unset the global cpuidle driver variable.
120 * @drv: a pointer to a struct cpuidle_driver
121 *
122 * Reset the global cpuidle variable to NULL. If @drv does not match the
123 * registered driver, do nothing.
124 */
125static inline void __cpuidle_unset_driver(struct cpuidle_driver *drv)
126{
127 if (drv == cpuidle_curr_driver)
128 cpuidle_curr_driver = NULL;
129}
130
131#endif
132
133/**
134 * cpuidle_setup_broadcast_timer - enable/disable the broadcast timer on a cpu
135 * @arg: a void pointer used to match the SMP cross call API
136 *
137 * If @arg is NULL broadcast is disabled otherwise enabled
138 *
139 * This function is executed per CPU by an SMP cross call. It's not
140 * supposed to be called directly.
141 */
142static void cpuidle_setup_broadcast_timer(void *arg)
143{
144 if (arg)
145 tick_broadcast_enable();
146 else
147 tick_broadcast_disable();
148}
149
150/**
151 * __cpuidle_driver_init - initialize the driver's internal data
152 * @drv: a valid pointer to a struct cpuidle_driver
153 */
154static void __cpuidle_driver_init(struct cpuidle_driver *drv)
155{
156 int i;
157
158 /*
159 * Use all possible CPUs as the default, because if the kernel boots
160 * with some CPUs offline and then we online one of them, the CPU
161 * notifier has to know which driver to assign.
162 */
163 if (!drv->cpumask)
164 drv->cpumask = (struct cpumask *)cpu_possible_mask;
165
166 for (i = 0; i < drv->state_count; i++) {
167 struct cpuidle_state *s = &drv->states[i];
168
169 /*
170 * Look for the timer stop flag in the different states and if
171 * it is found, indicate that the broadcast timer has to be set
172 * up.
173 */
174 if (s->flags & CPUIDLE_FLAG_TIMER_STOP)
175 drv->bctimer = 1;
176
177 /*
178 * The core will use the target residency and exit latency
179 * values in nanoseconds, but allow drivers to provide them in
180 * microseconds too.
181 */
182 if (s->target_residency > 0)
183 s->target_residency_ns = s->target_residency * NSEC_PER_USEC;
184 else if (s->target_residency_ns < 0)
185 s->target_residency_ns = 0;
186 else
187 s->target_residency = div_u64(s->target_residency_ns, NSEC_PER_USEC);
188
189 if (s->exit_latency > 0)
190 s->exit_latency_ns = s->exit_latency * NSEC_PER_USEC;
191 else if (s->exit_latency_ns < 0)
192 s->exit_latency_ns = 0;
193 else
194 s->exit_latency = div_u64(s->exit_latency_ns, NSEC_PER_USEC);
195 }
196}
197
198/**
199 * __cpuidle_register_driver: register the driver
200 * @drv: a valid pointer to a struct cpuidle_driver
201 *
202 * Do some sanity checks, initialize the driver, assign the driver to the
203 * global cpuidle driver variable(s) and set up the broadcast timer if the
204 * cpuidle driver has some states that shut down the local timer.
205 *
206 * Returns 0 on success, a negative error code otherwise:
207 * * -EINVAL if the driver pointer is NULL or no idle states are available
208 * * -ENODEV if the cpuidle framework is disabled
209 * * -EBUSY if the driver is already assigned to the global variable(s)
210 */
211static int __cpuidle_register_driver(struct cpuidle_driver *drv)
212{
213 int ret;
214
215 if (!drv || !drv->state_count)
216 return -EINVAL;
217
218 ret = cpuidle_coupled_state_verify(drv);
219 if (ret)
220 return ret;
221
222 if (cpuidle_disabled())
223 return -ENODEV;
224
225 __cpuidle_driver_init(drv);
226
227 ret = __cpuidle_set_driver(drv);
228 if (ret)
229 return ret;
230
231 if (drv->bctimer)
232 on_each_cpu_mask(drv->cpumask, cpuidle_setup_broadcast_timer,
233 (void *)1, 1);
234
235 return 0;
236}
237
238/**
239 * __cpuidle_unregister_driver - unregister the driver
240 * @drv: a valid pointer to a struct cpuidle_driver
241 *
242 * Check if the driver is no longer in use, reset the global cpuidle driver
243 * variable(s) and disable the timer broadcast notification mechanism if it was
244 * in use.
245 *
246 */
247static void __cpuidle_unregister_driver(struct cpuidle_driver *drv)
248{
249 if (drv->bctimer) {
250 drv->bctimer = 0;
251 on_each_cpu_mask(drv->cpumask, cpuidle_setup_broadcast_timer,
252 NULL, 1);
253 }
254
255 __cpuidle_unset_driver(drv);
256}
257
258/**
259 * cpuidle_register_driver - registers a driver
260 * @drv: a pointer to a valid struct cpuidle_driver
261 *
262 * Register the driver under a lock to prevent concurrent attempts to
263 * [un]register the driver from occuring at the same time.
264 *
265 * Returns 0 on success, a negative error code (returned by
266 * __cpuidle_register_driver()) otherwise.
267 */
268int cpuidle_register_driver(struct cpuidle_driver *drv)
269{
270 struct cpuidle_governor *gov;
271 int ret;
272
273 spin_lock(&cpuidle_driver_lock);
274 ret = __cpuidle_register_driver(drv);
275 spin_unlock(&cpuidle_driver_lock);
276
277 if (!ret && !strlen(param_governor) && drv->governor &&
278 (cpuidle_get_driver() == drv)) {
279 mutex_lock(&cpuidle_lock);
280 gov = cpuidle_find_governor(drv->governor);
281 if (gov) {
282 cpuidle_prev_governor = cpuidle_curr_governor;
283 if (cpuidle_switch_governor(gov) < 0)
284 cpuidle_prev_governor = NULL;
285 }
286 mutex_unlock(&cpuidle_lock);
287 }
288
289 return ret;
290}
291EXPORT_SYMBOL_GPL(cpuidle_register_driver);
292
293/**
294 * cpuidle_unregister_driver - unregisters a driver
295 * @drv: a pointer to a valid struct cpuidle_driver
296 *
297 * Unregisters the cpuidle driver under a lock to prevent concurrent attempts
298 * to [un]register the driver from occuring at the same time. @drv has to
299 * match the currently registered driver.
300 */
301void cpuidle_unregister_driver(struct cpuidle_driver *drv)
302{
303 bool enabled = (cpuidle_get_driver() == drv);
304
305 spin_lock(&cpuidle_driver_lock);
306 __cpuidle_unregister_driver(drv);
307 spin_unlock(&cpuidle_driver_lock);
308
309 if (!enabled)
310 return;
311
312 mutex_lock(&cpuidle_lock);
313 if (cpuidle_prev_governor) {
314 if (!cpuidle_switch_governor(cpuidle_prev_governor))
315 cpuidle_prev_governor = NULL;
316 }
317 mutex_unlock(&cpuidle_lock);
318}
319EXPORT_SYMBOL_GPL(cpuidle_unregister_driver);
320
321/**
322 * cpuidle_get_driver - return the driver tied to the current CPU.
323 *
324 * Returns a struct cpuidle_driver pointer, or NULL if no driver is registered.
325 */
326struct cpuidle_driver *cpuidle_get_driver(void)
327{
328 struct cpuidle_driver *drv;
329 int cpu;
330
331 cpu = get_cpu();
332 drv = __cpuidle_get_cpu_driver(cpu);
333 put_cpu();
334
335 return drv;
336}
337EXPORT_SYMBOL_GPL(cpuidle_get_driver);
338
339/**
340 * cpuidle_get_cpu_driver - return the driver registered for a CPU.
341 * @dev: a valid pointer to a struct cpuidle_device
342 *
343 * Returns a struct cpuidle_driver pointer, or NULL if no driver is registered
344 * for the CPU associated with @dev.
345 */
346struct cpuidle_driver *cpuidle_get_cpu_driver(struct cpuidle_device *dev)
347{
348 if (!dev)
349 return NULL;
350
351 return __cpuidle_get_cpu_driver(dev->cpu);
352}
353EXPORT_SYMBOL_GPL(cpuidle_get_cpu_driver);
354
355/**
356 * cpuidle_driver_state_disabled - Disable or enable an idle state
357 * @drv: cpuidle driver owning the state
358 * @idx: State index
359 * @disable: Whether or not to disable the state
360 */
361void cpuidle_driver_state_disabled(struct cpuidle_driver *drv, int idx,
362 bool disable)
363{
364 unsigned int cpu;
365
366 mutex_lock(&cpuidle_lock);
367
368 spin_lock(&cpuidle_driver_lock);
369
370 if (!drv->cpumask) {
371 drv->states[idx].flags |= CPUIDLE_FLAG_UNUSABLE;
372 goto unlock;
373 }
374
375 for_each_cpu(cpu, drv->cpumask) {
376 struct cpuidle_device *dev = per_cpu(cpuidle_devices, cpu);
377
378 if (!dev)
379 continue;
380
381 if (disable)
382 dev->states_usage[idx].disable |= CPUIDLE_STATE_DISABLED_BY_DRIVER;
383 else
384 dev->states_usage[idx].disable &= ~CPUIDLE_STATE_DISABLED_BY_DRIVER;
385 }
386
387unlock:
388 spin_unlock(&cpuidle_driver_lock);
389
390 mutex_unlock(&cpuidle_lock);
391}
1/*
2 * driver.c - driver support
3 *
4 * (C) 2006-2007 Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
5 * Shaohua Li <shaohua.li@intel.com>
6 * Adam Belay <abelay@novell.com>
7 *
8 * This code is licenced under the GPL.
9 */
10
11#include <linux/mutex.h>
12#include <linux/module.h>
13#include <linux/cpuidle.h>
14
15#include "cpuidle.h"
16
17static struct cpuidle_driver *cpuidle_curr_driver;
18DEFINE_SPINLOCK(cpuidle_driver_lock);
19
20/**
21 * cpuidle_register_driver - registers a driver
22 * @drv: the driver
23 */
24int cpuidle_register_driver(struct cpuidle_driver *drv)
25{
26 if (!drv)
27 return -EINVAL;
28
29 if (cpuidle_disabled())
30 return -ENODEV;
31
32 spin_lock(&cpuidle_driver_lock);
33 if (cpuidle_curr_driver) {
34 spin_unlock(&cpuidle_driver_lock);
35 return -EBUSY;
36 }
37 cpuidle_curr_driver = drv;
38 spin_unlock(&cpuidle_driver_lock);
39
40 return 0;
41}
42
43EXPORT_SYMBOL_GPL(cpuidle_register_driver);
44
45/**
46 * cpuidle_get_driver - return the current driver
47 */
48struct cpuidle_driver *cpuidle_get_driver(void)
49{
50 return cpuidle_curr_driver;
51}
52EXPORT_SYMBOL_GPL(cpuidle_get_driver);
53
54/**
55 * cpuidle_unregister_driver - unregisters a driver
56 * @drv: the driver
57 */
58void cpuidle_unregister_driver(struct cpuidle_driver *drv)
59{
60 if (drv != cpuidle_curr_driver) {
61 WARN(1, "invalid cpuidle_unregister_driver(%s)\n",
62 drv->name);
63 return;
64 }
65
66 spin_lock(&cpuidle_driver_lock);
67 cpuidle_curr_driver = NULL;
68 spin_unlock(&cpuidle_driver_lock);
69}
70
71EXPORT_SYMBOL_GPL(cpuidle_unregister_driver);